Studies in three major areas will be conducted: (1) Estradiol suppresses gonadotropin secretion in normal and amenorrheic women. Once estradiol is discontinued, gonadotropin levels increase again in normal individuals but not in patients with amenorrhea. The mechanism underlying this continued suppression will be evaluated by analyzing the pattern of LH and FSH secretion in response to LRF. (2) The Hre rat is an animal with an inherited disorder of sperm maturation. These animals are initially fertile but develop progressive oligospermia and infertility. A variety of studies have suggested abnormal Sertoli cell function. The pituitary-gonadal axis of these animals will be thoroughly evaluated by measuring gonadotropins and testosterone secretion in response to standard suppression and stimulation tests. Androgen binding protein biosynthesis will be studied by measuring amino acid incorporation into this protein following FSH stimulation. (3) The androgen receptor in kidney will be extensively purified by conventional and affinity chromatography. Sufficient quantities of this receptor will be prepared to permit studies of steroid receptor complex binding to mouse kidney chromatin. By this approach, we can examine the factors which control the magnitude of the androgen induced response. BIBLIOGRAPHIC REFERENCES: Bardin, C.W., L.P. Bullock, O. Janne, and S.T. Jacob: Genetic regulation of the androgen receptor: A study of testicular feminization in the mouse. J. Steroid Biochem. 6: 515-520, 1975. Bardin, C.W., O. Janne, L.P. Bullock and S.T. Jacob. Physiochemical and biological properties of androgen receptors. In Proceedings of 2nd Annual Testes Workshop, F. French, ed., Plenum Press, 1975, p. 237-256.